Arsenic distribution and pathway scenarios for sediments and water in a peri-urban Mongolian small-scale coal mining area (Nalaikh District, Ulaanbaatar)

The impacts of mining on soil pollution with metal(loid)s in resource-rich Mongolia

“…IPI N assessment classified all the towns as safe according to average IPI N values (Table S1). Therefore, despite the ongoing open-pit mining (Baganuur, Sharyn Gol) or historical underground mining (Nalaikh) of coal enriched with chalcophile elements 7,17,23,29 , the results suggest minor pollution with Cd, Cu, Pb and Zn. Dependence of the soil contamination to pollution distribution on the mine's proximity is rather indirect or none (Fig.…”

“…These towns are or were main coal suppliers to the three largest Mongolian cities: Ulaanbaatar, Erdenet and Darkhan 17,29,30 . While official mining in Nalaikh has already ended 22 , small-scale illegal mining continues 7 . The open-pit (Baganuur, Sharyn Gol) or underground (Nalaikh) coal mines are to the south of the towns.…”

“…Its rapid development associated with the intensive release of mining licensing began in the 1990s after the transition to an open economy and is ongoing 4,5 . Simultaneously, the expansion of major official mining operations has been accompanied by artisanal and smallscale mining 6,7 . There are approximately 3,000 deposits and 50 different minerals explored and researched in Mongolia 1 , with the most economically important and mined commodities being black and brown coal, fluorite, Au, Cu, Ag, Mo, Pb and Zn 8,9 .However, mining development and related economic growth have accelerated land degradation 10 .…”

Arsenic pollution in Quaternary sediments and water near a former gold mine

“…Moreover, As content (72–451 mg/kg) in soils in allotment gardens suppling inhabitants of Złoty Stok with fruits and vegetables markedly exceeds soil quality limits 37 . High levels of bioaccumulation over a wide range of crops may affect the inclusion As in food consumed by inhabitants and domestic animals 15 . Additionally, in forested areas surrounding croplands, decomposition of forest litter leads to an increased share of highly mobile As species 93 , 94 increasing their transfer to the surrounding arable lands.…”

“…Moreover, variation in the physiochemical properties of water (e.g. pH, water temperature 12 , 13 ), meteorological conditions (evaporation 12 , 14 , 15 ), suspended sediment and organic matter transport 14 , water residence time 16 , groundwater withdrawal 17 , and concentrations of phosphate and iron oxides 14 , 18 , 19 affect the seasonal dynamics of arsenic species in surface waters. For example, the summer (as opposed to winter) season, with its high air and water temperatures, leads to an increase in As mass fluxes 12 – 14 .…”